"We under-performed in Broward and Dade", said Democratic booster Chris Korge, who helped organize big-money fundraisers for Gillum with Hillary Clinton.
The president injected himself into the race in December when, while taxiing on Air Force One on the runway at Palm Beach International Airport, he tweeted that DeSantis "would make a GREAT Governor of Florida".
Nelson is defending his seat against Scott, the current governor.
While much of focus of the elections on Tuesday was on which party would win control of the U.S. Congress, Republicans and Democrats were battling across the country for state-level power, which could have a major impact on issues such as congressional redistricting and healthcare. He enjoyed support from President Trump throughout his campaign.
Asked what it would mean for the state if he wins, Gillum said: 'Us winning tonight I think will send a message to Mr. Trump and Mr. DeSantis as well that the politics of hatred and of division and of separation, that they come to an end, at least in this election, that's what we're going to show. Instead of throwing all their efforts into election cycles, Olivia Bercow, a NextGen America spokeswoman, said Democrats should immediately get back to bench-building and registering voters.
"I think even in conceding that this is such a close race that DeSantis has to hear that this is a state divided and that our voices still need to be heard", said Chris Lucas.
The gubernatorial race was a study in contrasts: a straight-talking, unapologetically progressive, black nominee running against a Tea Party figure who released a campaign ad in which his young children built Trump's fabled border wall out of toy bricks.
Tallahassee Mayor Andrew Gillum and his wife R. Jai voted Tuesday morning at a church in the northside of the city.
Fox News projected DeSantis, a former congressman, would win with 99 percent of precincts reporting.
During his acceptance speech, Gillum thanked his wife and Trump for their support. Bill Nelson was hoping a recount would reverse Republican Gov. Rick Scott's narrow lead.
Both Abrams and Gillum were targeted by racist robo-calls to voters from a white supremacist group that both parties denounced.
"Political campaigns are a rough business and often about highlighting our differences".
DeSantis' apparent victory marked a bright spot on a mixed night for Republicans, who lost control of the House while retaining control of the Senate. That ethics probe recently revealed that he'd accepted tickets to the Broadway musical "Hamilton" from the undercover Federal Bureau of Investigation agent in 2016.